1. Field of the Invention
The present invention relates generally to the field of optics, and more particularly to systems and methods for aligning, qualifying, or designing optical systems.
2. Background of the Invention
The alignment of optical elements, such as lens, detectors, emitters, optical subassemblies, lasers, light emitting diodes, and the like, is generally a very important aspect for optical systems or assemblies. Alignment is typically performed by aligning optical elements to the location where the highest power coupled or transmitted between the optical elements. Alignment is typically performed using automated systems having fixtures for holding one or more optical elements in known, fixed positions and a motor or motors attached to a stage or stages that move one or more optical elements relative to the fixed element. A stage may move the optical element in the x, y, and z directions while detectors monitor the output power. For example, an alignment system may include fixing the end of a fiber optic and moving an optical element, such as lasers, light emitting diode (LED), vertical cavity surface emitting lasers (VCSELs), lens, receivers, and optical fiber, while a video system and/or power meters monitors the power coupled into an optical element or into the fiber optic cable. Such systems generally align the elements to the point of peak coupled power, that is, the point of highest power transferred between the two optical elements.
However, this alignment approach may not produce the best alignment for a number of reasons. For example, depending upon the optics and the nature of the light source, the peak coupled power might occur at a position where the coupled power drops drastically from the peak power. Therefore, if a part in an assembly was aligned to the point of peak power, the assembly would have very limited tolerance to subsequent changes. These changes might occur when the assembly is exposed to mechanical forces, which might flex the part and change the effective alignment. Changes may also result from temperature changes, which may change the effective refractive index of optical components or the curvature of a lens and thereby change the focal point. Furthermore, aligning the parts to the peak coupled power may not necessarily result in the optimization of other performance characteristics that may be critical to assembly's utility. Therefore, it is important that the coupling occurs not only at the proper power levels but also at the proper location.
Furthermore, the quality of an optical element is generally checked by determining whether the optical element couples the correct power. However, as noted above, although the optical element may couple a sufficient level of power at one location, this point of peak coupled power may not be in the proper location, or it may have an unacceptable distribution.
Accordingly, there is a need for more robust alignment systems and methods for aligning, qualifying, or designing optical elements.